/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.distributedlog.common.rate;

import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.TimeUnit;

/**
 * Factory to create {@link MovingAverageRate} instances.
 */
public class MovingAverageRateFactory implements Runnable {

    private static final int DEFAULT_INTERVAL_SECS = 1;

    private final ScheduledExecutorService scheduler;
    private final ScheduledFuture<?> scheduledFuture;
    private final CopyOnWriteArrayList<SampledMovingAverageRate> avgs;

    public MovingAverageRateFactory(ScheduledExecutorService scheduler) {
        this.avgs = new CopyOnWriteArrayList<SampledMovingAverageRate>();
        this.scheduler = scheduler;
        this.scheduledFuture = this.scheduler.scheduleAtFixedRate(
            this, DEFAULT_INTERVAL_SECS, DEFAULT_INTERVAL_SECS, TimeUnit.SECONDS);
    }

    public MovingAverageRate create(int intervalSecs) {
        SampledMovingAverageRate avg = new SampledMovingAverageRate(intervalSecs);
        avgs.add(avg);
        return avg;
    }

    public void close() {
        scheduledFuture.cancel(true);
        avgs.clear();
    }

    @Override
    public void run() {
        sampleAll();
    }

    private void sampleAll() {
        avgs.forEach(SampledMovingAverageRate::sample);
    }
}
